The largest hot spring in the United States, and the third-largest in the world. 

A historic and archaeological city in southern Jordan inhabited as early as the 4th century BC.

The largest religious structure in the world by land area.

A group of very large geoglyphs made in the soil of the Nazca Desert in southern Peru

Otherworldly colors mimic a rainbow painted over the tops of rolling mountains.

A cave known for its population of Arachnocampa luminosa, a glowworm species found exclusively in New Zealand.

Formed by the erosion of Navajo Sandstone due to flash flooding.

The world's largest salt flat at over 10,000 square km.

Pamukkale, meaning "cotton castle" in Turkish, is a natural site famous for a carbonate mineral left by the flowing of thermal spring waters.

Thermophilic algae, which flourish in moist, hot environments, color the rocks resulting in multiple hues of green and red.

Over thousands of years, mineral-rich glacier water has changed the color and shape of the Marble Cave formations to beautiful hues of blues, greens, blacks, and yellows.

Consists of intersecting U-shaped troughs that have been eroded into Navajo Sandstone of Jurassic age.